Question

Mention the most significant function of each of the following
(i) Tapetum cells
(ii) Serotonin
(iii) Lenticels
(iv) Cerebrospinal fluid
(v) Islets of Langerhans
(vi) Bundle sheath

Answer 1

Hint: The tapetum is a specialized layer of nutritive cells found within the anther. Serotonin is a chemical in the human body and it is sometimes called a happy chemical because it contributes to wellbeing and happiness. Lenticels are portions of the periderm that have numerous pores or intercellular spaces. Cerebrospinal fluid is a clear, colorless body fluid found in the brain and spinal cord. Islets of Langerhans are a group of pancreatic cells secreting insulin and glucagon. Bundle sheath is a layer or region of compactly arranged cells surrounding a vascular bundle in a plant.

Complete answer:
Tapetum is a nutritive cell found in the anther of flowering plants, where it is located between the sporogenous tissue and the anther wall. Tapetum is important for the nutrition and development of pollen grains, as well as a source of precursors for the pollen coat.
Serotonin has a significant role in the human body. It is believed to help regulate mood and social behavior, appetite and digestion, sleep, memory, and sexual desire and function.
Lenticels are one of the small areas on the surface of a plant stem, trunk, or fruit that allow the interchange of gases between the metabolically active interior tissue and the surrounding air or pockets of air in the soil.
Cerebrospinal fluid assists the brain by providing protection, nourishment, and waste removal. It provides hydromechanical protection of the neuraxis through two mechanisms. First, CSF acts as a shock absorber, cushioning the brain against the skull.
The islets of Langerhans are a cluster of cells within the pancreas that are responsible for the production and release of hormones.
The bundle sheaths regulate the movement of substances between the vascular tissue and the parenchyma and, in leaves, protect the vascular tissue from exposure to air.

Additional Information:
- Serotonin is a neurotransmitter that is acetylated and then methylated within the pineal gland to produce melatonin. It is believed that there may be a link between serotonin and depression.
- Tapetum cell is the fourth and innermost layer of the microsporangium.
- Lenticels function as a pore, providing a pathway for the direct exchange of gases between the internal tissues and atmosphere through the bark, which is otherwise impermeable to gases.

Note:
- Cerebrospinal fluid acts as the cushion for the brain and acts as the shock absorber for the central nervous system.
- Islets of Langerhans also called pancreatic islets contain many cells including the beta cells that secrete insulin.
- In ${ C }_{ 4 }$ plants the bundle sheath cells contain chloroplasts and are the site of the Calvin cycle.